1. Technical Field
The present invention relates to a lighting device for turning on a discharge lamp and a projector.
2. Related Art
A projector which includes a light source, a light modulation device for modulating light emitted from the light source to form an image corresponding to image information, and a projection device for projecting the formed image is known. The light source included in this projector is often constituted by a discharge lamp such as an extra-high pressure mercury lamp containing a discharge space into which a pair of electrodes and discharge substances are sealed. In this case, a lighting control device for controlling lighting of the discharge lamp is equipped. A known type of this lighting control device includes a lighting device for supplying lamp power to the discharge lamp to turn on the discharge lamp, and a control device (control circuit) for controlling the operation of the lighting device (for example, see JP-A-2009-54365).
The lighting control device (high-pressure discharge lamp lighting device) disclosed in JP-A-2009-54365 includes a chopper circuit, a full-bridge circuit, a resonating circuit, and an igniter circuit.
The chopper circuit reduces voltage received from a direct current power source and outputs the reduced voltage to the full-bridge circuit. The full-bridge circuit converts the received direct current into alternating current and supplies the converted current to a high-pressure discharge lamp. The resonating circuit resonates by switching operation of the full-bridge circuit and produces high voltage. The igniter circuit generates pulse voltage for starting the high-pressure discharge lamp by using the high voltage produced by the resonating circuit.
It is known that a discharge lamp left in a cold and dark place comes into a hold condition where light emission substances sealed within the discharge lamp are not easily activated. Thus, for turning on the discharge lamp in this condition, lighting start voltage higher than usual is applied to the discharge lamp, for example.
According to the lighting control device shown in JP-A-2009-54365, however, the resonating circuit provided in addition to the igniter circuit generates high voltage. The high voltage thus produced can break insulation between electrodes of the discharge lamp left in the cold and dark place.
According to the lighting control device shown in JP-A-2009-54365 which has the resonating circuit and the igniter circuit separately, however, the structure of the lighting device becomes complicated. In addition, since high voltage is produced on the downstream side of the resonating circuit, a substrate, circuit elements and other components easily deteriorate.